Hiller, GudrunBoer, Stefan de2017-08-072017-08-072017http://hdl.handle.net/2003/36043http://dx.doi.org/10.17877/DE290R-18060This thesis comprises a study of rare charm decays in the standard model (SM) and beyond. Within an effective theory framework, we calculate the SM Wilson coefficients to (partly) next-to-next-to leading logarithmic order in quantumchromodynamics. The calculation includes matching conditions and the running of the Wilson coefficients in the renormalization group-improved perturbation theory, thereby correcting expressions used in the literature. Furthermore, a calculation of phenomenological relevant two loop matrix elements of current-current operators is presented. We work out the phenomenology in the SM for radiative and semileptonic inclusive decays as well as the exclusive decays D -> Pll and D -> V gamma, including non-perturbative effects. The branching ratios are dominated by resonances, yet we can construct various observables which cleanly probe the SM, e.g. asymmetries, angular observables and lepton flavor violating decays are (approximate) SM null tests. Beyond the SM physics effects are analyzed model-independently and via leptoquark models, where various constraints and correlations, e.g. through flavor patterns, are worked out. In addition, we probe the SM by means of the decay Lambda_c -> p gamma, which is accessible at (future) colliders, and investigate the radiative decays in supersymmetric models.enSeltene ZerfälleCharmFlavorStandardmodellLeptoquarksWilson Koeffizienten530TextCharmFlavour <Elementarteilchen>Leptoquark